Abstract
Hypertonic saline (HTS) is a group of fluids containing sodium and chloride in a higher concentration as compared to physiological saline. The authors have conducted this review to evaluate the use of HTS in neuroanesthesia and neurocritical care. The articles for this narrative review on HTS were searched on databases like PubMed Central, EMBASE, and Google Scholar using the Medical Subject Headings keywords “Hypertonic Saline,” “Neuroanesthesia,” and “Neurocritical Care.” The review focuses on the mechanisms of HTS and its in routine clinical practice. The results of various comparative studies between HTS and mannitol and guidelines regarding the use of HTS have also been reviewed. HTS can be used to treat hyponatremia, reduce intracranial pressure, provide intraoperative relaxed brain, and aid in resuscitation during cardiogenic, neurogenic, and septic shock. Its side effects include renal toxicity in the case of hypernatremia, rebound intracranial hypertension, volume overload, dyselectrolytemia, phlebitis, local tissue damage, and osmotic demyelination syndrome in the case of rapid correction of serum sodium concentration.
Key Points
- Mechanism of Action: HTS primarily reduces ICP through osmotic shifts, pulling water from intracellular and interstitial spaces into the vascular compartment. It also improves cerebral perfusion pressure (CPP) and reduces neuronal toxicity by modulating ion exchange mechanisms. Additionally, HTS has vascular, hemodynamic, immunologic, and neurochemical effects that contribute to neuroprotection.
- Comparison with Mannitol in ICP Management: Studies comparing HTS with mannitol indicate that HTS provides a more sustained reduction in ICP and CPP improvement. However, meta-analyses suggest that HTS does not provide a clear survival benefit over mannitol.
- HTS in Traumatic Brain Injury (TBI): HTS has been widely studied in TBI patients for ICP management. While some studies show that it effectively reduces ICP and improves CPP, others indicate that it does not significantly reduce the need for additional interventions.
- Use in Subarachnoid Hemorrhage (SAH): HTS has been used in SAH patients to reduce ICP and improve cerebral blood flow (CBF). Studies have demonstrated an increase in tissue oxygenation and improved hemodynamics following HTS administration.
- Application in Stroke Patients: HTS has been explored as an alternative to mannitol for managing cerebral edema in ischemic and hemorrhagic strokes. While it effectively lowers ICP, no significant mortality benefit has been established.
- HTS in Intraoperative Brain Relaxation: Studies have shown that HTS achieves intraoperative brain relaxation comparable to mannitol, with the added benefit of hemodynamic stability. It is considered an effective alternative hyperosmolar agent in neurosurgical procedures.
- HTS in Shock Management: HTS has been investigated for use in hypovolemic, cardiogenic, neurogenic, and septic shock. It enhances cardiac output and tissue perfusion but has not demonstrated long-term survival benefits. In neurogenic shock, it reduces spinal cord edema and mitigates secondary injury.
- Complications and Risks: Potential adverse effects of HTS include renal impairment, rebound intracranial hypertension, osmotic demyelination syndrome, hyperchloremic metabolic acidosis, and volume overload. Phlebitis and coagulation dysfunction have been reported with large-volume infusions.
- Guidelines and Recommendations: While HTS is recommended for pediatric TBI management, no consensus favors it over mannitol in adult neurocritical care. The Brain Trauma Foundation (BTF) and the Neurocritical Care Society (NCS) acknowledge HTS as an alternative osmotherapy but do not consider it superior to mannitol.
- Future Directions: Further research is needed to refine the indications, dosing strategies, and long-term safety of HTS in neurocritical care. The role of advanced monitoring techniques, such as cerebral oximetry and multimodal imaging, should be explored to optimize HTS use in individual patients.
